The article "All-Optical FM mode-locking of fiber laser" from the Electronic Letters of Aug. 1992, pages 1741-1743 by E. J. Greer and K. Smith, describes a fiber laser for producing optical pulses. The fiber laser is configured as a ring laser with an erbium-doped fiber, an optical filter, a fiber modulator and several couplers. The fiber modulator is driven by optical pulses. The optical pulses briefly change the index of refraction of the fiber modulator, changing the phase of the continuous radiation (CW-operation) produced in the erbium-doped fiber. This leads to interference and thus to the generation of optical pulses at the laser output. To obtain sufficient modulation effect, i.e. a sufficiently large phase shift, it is necessary to construct the fiber modulator from an 8.8 km long fiber, which can negatively influence the operation of the fiber laser, e.g. due to production tolerances. This fiber laser is particularly sensitive to temperature because of the 8.8 km long fiber.